JPS5929501A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the durability of a tire by such an arrangement wherein a piece of synthetic fiber filament is used as a core strand, and a covering layer made of organic high polymer is provided only around the core strand, and further steel filaments are wrapped around the outer circumference of the core strand, etc. CONSTITUTION:A core strand 6 is composed by forming a covering layer 6b made of organic high polymer around the outer periphery of a piece of synthetic fiber filament 6a and 4 pieces of side strand 7 made of steel filament are wrapped around the outer periphery of the core strand 6 and free spaces 8 are formed between side strands 7. By this arrangement wherein wires are stranded so that they are not brought to tightly contact each other and sealed voids are not generated inside the strand, such a trouble can be avoided that rubber is filled up and water penetrates into the strand along voids. Consequently, steel cords are prevented from becoming rusty.

Description

[Detailed description of the invention] This invention relates to pneumatic tires.

In recent years, automobiles have become faster due to improvements in automobile performance and the expansion of highway networks, and steel cords are now widely used in tire breakers as automatic military tires that can withstand high speeds. Conventionally, the steel cord used in the single layer of the breaker has generally been made by twisting strands of four to six steel wires into a concentric pattern.

For example, the steel cord in Figure 1 is made by twisting four wooden strands 1, and the steel cord in Figure 2 is made by twisting six wooden side strands 3 around one core strand 2. It is something that As shown in Figures 1 and 2 above, the steel cord is made by twisting the strands closely together.
A sealed cavity 4 or 5 is formed inside it. If such a steel cord is buried in one layer of rubber in the breaker, the above-mentioned closely spaced gap 4.5 will not be filled with rubber, so if the tread part of the radial tire is damaged by external trauma, water will leak out from the damaged part. If the water penetrates into the steel cord, the water spreads through the gaps in the steel cord, causing rust on the edge record, and this rust makes it easy for the layers of the breaker to separate.

! ! Since the strands of wires are in close contact with each other, the strands are worn out due to friction between the strands and the so-called fretting phenomenon, reducing fatigue resistance. Furthermore, since the steel cords are compact and close to each other, the outer diameter of the steel cord is small and the steel cord does not cover the tire tread sufficiently, so the nails inserted into the tire may be obstructed by the steel hood. In some cases, the particles could penetrate deep inside the vehicle and damage the tires.

In order to eliminate the above-mentioned drawbacks, the applicant previously
As shown in FIG. 3, we have proposed a steel cord for automobile tires in which at least three side strands 7 are wound around the outer periphery of a wooden core strand 6 so as to have a free space 8 between them. (See Publication No. 56-31.090). however,
In the steel cord proposed above, when the side strands are wound around the outer periphery of the core strand and twisted together, the lateral strands tend to slip and shift their position, which may cause uneven twisting pitch in some areas. Furthermore, even if the cross-sectional structure is normal when the steel cords are twisted together, the cross-sectional shape of the rubber G changes as shown in Fig. 4 during the tire manufacturing process such as topping, cutting, molding, and vulcanization. It has been found that there is a problem in that the free space 8 between the side strands 7 and 7 is lost and a closed gap 9 is formed due to the deformation of the tire, which causes rust to develop and cause peeling and tire damage due to fatigue. Especially carbon content 0.
It is made of steel filament with 75 to 0.85 LTI amount%, and the steel cord is the formula% formula% (in the two formulas, ■) is the diameter of the steel filament, N
Vi is the number of steel filaments, W is the steel cord l. 1) Weight per unit F, TS is the tensile strength. If a steel cord is used, the toughness of the cord may deteriorate.

The core wire is made of organic fiber, and the outer circumference of the core wire is 3
~5 A steel cord (International Publication No. WO 30/2572) in which wooden side strands are wound so that they have free space between them is known, but this steel cord also has the same problems as mentioned above. .

On the other hand, a reinforcing layer steel cord (see Utility Model Application Publication No. 70304/1983) is known, which is made by twisting together a plurality of steel filament single wires coated with rubber in advance. As shown in Figure 2, the 11111 strands do not have free space, and all the side strands and core strands are covered with rubber, so the friction between the strands is large. There is a problem in that it becomes difficult to position each strand when twisting the wires together.

In order to eliminate the above-mentioned drawbacks, the present invention uses one synthetic fiber filament as a core wire, and provides only this core wire with a coating layer made of an organic polymer material.

That is, in the present invention, the steel cord forming one layer of the breaker has a core made of one synthetic fiber filament having a coating layer made of an organic polymer substance on the outer surface, and at least three fibers are arranged on the outer periphery of the core wire. This pneumatic tire is characterized in that steel filaments are wound around each other so as to have free space between them.

This EIJ1 [example of steel cord in Fig. 5] The outer periphery of the core wire 6a (one synthetic fiber filament) 6a is covered with a skin 6 made of an organic polymer material.
``b is formed by JF&, and the wire 7 is wound around the outer periphery of the core strand 6 with four wooden filllls made of steel filament, and the (111 strands 7.7 [1 old = 1:, is a free space 8
1. I'm here.

It is a monofilament consisting of three synthetic fiber filaments (core wire), Borienether, nylon, vinylon, aromatic polyamide, etc.

The organic polymer material covering the core wire 6 is natural rubber J1. Topping rubber made of synthetic rubber, resorcinol formaldehyde resin adhesive, etc.

It is formed by immersing a synthetic fiber filament in a solution of the above-mentioned organic polymeric substance, pulling it up, and then drying or cooling it.

i The thickness of the skin layer is preferably 0.01 to 0.07 mm L<,
If the thickness is less than 0.001 mm, the coating layer will easily peel off during the steel cord recognition process, and if the thickness exceeds 0.071 mm, the coating layer will stick to rollers during the topping process, and when the steel cord is pulled out. It takes a lot of force to
In addition, the topping cord h may warp, reducing the efficiency of the cutting process and the tie A' forming process.

In the example shown in FIG. 5 above, the synthetic fiber filament and the steel filament are shown to have the same thickness, but the thicknesses of both filaments do not have to be the same.

The number of side strands is at least three, and if the number of Bil+ strands is one or two, the shape of the steel cord becomes unstable. When the thickness of the core strand and the side strands are the same, the number of side strands is 3 to 5, and when there are 6 fl11 strands, the structure is the same as that shown in Figure 2. Therefore, no free space is formed between the side strands. If the core strand is thicker than the regular strand, a free space can be formed even if the number of side strands is six or more.

(The free space G formed between the 111 strands is calculated using the following formula:
~ In the above formula, d is the diameter of the core wire including the coating layer, and the value measured as g is calculated according to the following formula.

In the above formula, W is the hammer weight (kq), L is the arm length (crn), and θ is the arm swing angle after the sample is broken, θ.

is the arm swing angle when no sample is attached, and e is the trial t1 length (
cm), S indicates the sample cross-sectional area (c+#).

i! The calculated value of the free space is the calculated value (G) according to the formula, and the latter value is the calculated value (G) using the formula, and the latter value is the value when the steel cord is connected from one reel to five pulleys (diameter 50). The operation of passing the steel cord through the wire in a zigzag shape bent at right angles and winding it on the other reel is repeated 20 times. This shows the maximum value measured with makeup. The fact that the free space changes significantly before and after winding indicates that the side strands are displaced and the steel cord loses its shape, and the cord of comparative example D=E without a coating layer does not lose its shape. It represents something big.

(2) Tire The steel cord above is used as a breaker layer, and the polyester cord (1500 (IX2) i carcass layer is layered.
All 658R1g automobile tires were manufactured. The number of ends in one layer of the above breaker is 20 pieces/2.54C1n when the side element wire is a 5WSR82A cord, and 23 pieces/2.54CM when the side element wire is a 5WSR72A saw, the cord angle is 20 degrees, and the number of breaker pieces is 1. is 2 pieces.

The rubber composition used for manufacturing the tire was as shown below, and this rubber composition was also used for the coating layer around the outer periphery of the core wire and the topping rubber.

Natural rubber 100 parts HAF
55ZnO7 Stearic acid 2-trimethyldihydroquinoline polymer 2S i Ox
B resorcinol
25 melamine derivative
25 Cobalt naphthenate
2,5 Iou
4cyclohexylbenzthiazylsulfenamide
0.8 (3) Tire performance test The tire performance test is shown in Table 2 below.The salt damage drum test in the table above is conducted by drilling a 3-diameter hole between the inside of the tire and the first layer of the breaker. Open 8 locations around the circumference of the tire at equal intervals, inject 500cc of 5% saline solution into the hollow part, and apply a load of JIS 100%.
A drum rotation test was conducted at a tire air pressure of 1.7 kq/c and a running speed of 40 km/hour. The tire of the present invention showed no tire damage even after a mileage of 165,007 km, but the tire of the comparative example suffered damage after a mileage of 2,100 km, and the cause was rust on the steel cord.

In the salt damage test course test, a through hole with a diameter of 3 m77 was installed between the outside of the tire and the breaker layer under an air pressure of 1.
A car with tires of 7 kq/ctA speeds at 25 per hour.
km, remove the tire every 100 turns, take an X-ray photograph of the broken steel cord of the breaker layer, and calculate the number of turns when the cord breaks, and 200 turns.
It is indicated by the number of broken cords when turning.

For the breaker air permeation amount, a steel cord was extracted from a molded tire, and one steel cord cut to 6α was inserted into the center of a rubber compound block with a length of 5 on, width of 2.5a, and thickness of 2.51. Later, the pressure was increased to 30 k.
Vulcanize at q/cl, then grind both ends of the 1φ width direction of this vulcanized block with a grinder to a length of 5 cm, and then fully inject compressed air at a pressure of 5 kqlCJJ into one end of the block to make the rubber block. This is the amount of air flowing out from the other end measured with a flow meter.

As explained in 2, in the pneumatic tire of the present invention, the steel cords have free space between each other even after the tire is molded, and even in salt damage tests and figure 8 turning tests, the occurrence of cord breakage is reduced, and durability is improved. sex is improving.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of a conventional steel cord in which the wires are twisted closely together; Figure 3 is a cross-sectional view of a steel cord that is the mJ structure of the present invention;
The figure is a sectional view showing the steel cord shown in FIG. 3 having lost its shape in the tire, and FIG. 5 is a sectional view of an embodiment of the present invention. 6: Core strand, 6a: Covering layer, 7: Side strand, 8: Free space. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] [l] A steel cord forming one layer of the breaker has a single synthetic fiber filament having a coating layer made of a child polymer material on the outer surface as a core wire, and the outer surface of the core wire is 178, at least three steel filaments I-'z are wound around each other so as to have free space, or resorcinol-formaldehyde resin-based enclosing agent is used, and the thickness thereof is 0.
．． A pneumatic tire according to claim 1, having a diameter of 0.01 to 0.07 mm. [3] The pneumatic tire according to claim 1 or 2, wherein the synthetic fiber filament forming the core wire is a nylon monofilament. [11] Claim 1 in which the number of side strands is 3 to 5
Air tie-X' according to any one of items 3 to 3. [5] The steel filament forming the side wire has a carbon content fm of 0.75 to 085%, and the steel cord has the formula % (in the above formula, D is the diameter πm of the steel filament, Nl
The patent has a tensile strength calculated as follows: d number of steel filaments, W is weight y per steel cord l777, PS is tensile strength kq, and the denominator 7.86 indicates the specific gravity of iron. An air tie A' according to any one of claims 1 to 4 f8.